In this study, mesoporous alumina was synthesized using aluminium isopropoxide as Al precursor and cationic surfactant cetyl trimethylammonium bromide (CTAB) as structure directing agent and it was tested in the dehydration reaction of fructose into 5-HMF. The experiments were carried out in a microwave reactor at 200 °C for 5 min. The various ratio of CTAB/Al₂O₃ and calcination temperature between 400 and 700 °C were selected as synthesis parameters. The synthesized samples were analyzed by BET and XRD. The highest surface area was obtained as 602.22 m²/g with the weight ratio of CTAB to Al₂O₃ of 1.00 at the calcination temperature of 400 °C. When calcination temperature increased from 400 to 700 °C, surface area decreased into 286.14 m²/g. N₂ adsorption/desorption isotherms of samples showed characteristic mesoporous type IV according to IUPAC classification. According to XRD patterns, all catalysts were in the amorphous structure. The maximum 5-HMF yield of 51% was achieved with the alumina catalyst calcined at 400 °C and CTAB/Al₂O₃ ratio of 1.0. Although the surface area decreased by rising the calcination temperature from 400 to 550 °C, the fructose conversion reached the highest value (97.54%).

中文翻译：

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十六烷基三甲基溴化铵定向介孔氧化铝催化剂上果糖合成5-羟甲基糠醛（5-HMF）：十六烷基三甲基溴化铵用量和煅烧温度的影响

本研究以异丙醇铝为铝前驱体，以阳离子表面活性剂十六烷基三甲基溴化铵（CTAB）为结构导向剂合成介孔氧化铝，并在果糖脱水生成5-HMF中进行了测试。实验在微波反应器中于200°C进行5分钟。选择CTAB / Al ₂ O ₃的不同比例和400至700℃之间的煅烧温度作为合成参数。通过BET和XRD分析合成的样品。CTAB与Al ₂ O ₃的重量比为602.22 m ² / g。在400°C的煅烧温度下为1.00。当煅烧温度从400℃升高至700℃时，表面积降低至286.14m ² / g。根据IUPAC分类，样品的N ₂吸附/解吸等温线显示出特征性的中孔IV型。根据XRD图谱，所有催化剂均处于无定形结构中。使用在400°C煅烧且CTAB / Al ₂ O ₃比为1.0的氧化铝催化剂，可以实现51％的5-HMF最高收率。尽管通过将煅烧温度从400升高到550°C减少了表面积，但果糖转化率却达到了最高值（97.54％）。